Positive displacement pump



Jan. 19, 1943. L. E. HARPER POSITIVE DISPLACEMENT PUMP 2 Sheets-Sheet 1Filed Nov. 1, 1939 Vm Qm a Ra Y m w Patented Jan. 19, 1943 UNITEDSTATES: PATENT OFFICE Claims.

My invention relates to positive displacement pumps, and moreparticularly to a liquid feeding device of a pump-like. character thatwill accurately meter the amount of liquid fed by each reciprocation ofthe pumping device.

It is a particular purpose of my invention to provide a positivedisplacement pump for accurately measuring small quantities of liquid.

In order to accomplish this purpose it is necessary that an exactquantity of liquid be discharged by the pump for each cycle of operationthereof, that is, for each intake and discharge stroke. Preferably, thisis accomplished by providing inlet and outlet valves for the pump, thatare positively closed so that the outlet valve will be positively closedbefore the intake, or suction stroke, of the pump begins, and so thatthe inlet valve will be positively closed before the discharge strokecommences, it being, of course,- also preferred, inasmuch as thematerial that is pumped is a substantially non-compressible liquid, thatthe outlet valve be opened at least as soon as the discharge strokebegins, and that the inlet valve be opened at least as soon as thesuction stroke begins.

It is a further purpose of my invention to provide a pumping device ofthe above mentioned character, which comprises a chamber that isprovided with an inlet and outlet connection,

- having positively operated valves controlling certain inlet and outletconnections, which are positively operated in apredetennined timedrelation to the strokes of a reciprocable member,

which varies the liquid capacity of the chamber, so-as to produceapumping action of the liquid that maybe received within the saidchamber from the inlet connection and discharged through the outletconnection. Preferably, the reciprocable means is operated in such amanner that there is an interval of short duration at the point ofreversal of motion thereof between the alternating strokes thereof,during which said reciprocable member is stationary for a sufficientperiod of time, so that the inlet valve can close and the outlet valveopen, and vice versa, without there being any possibility of there beingmovement of the reciprocable member in the wrong direction, while eitherthe inlet or the outlet valve is open, which would, of course, interferewith the accurate measurement of the liquid by means of the pumpingdevice.

Preferably, my improved pumping device embraces means for varying theamount of liquid pumped per stroke of the pump, so that the measuredamount of liquid furnished at a certain rate of rotation of the pump maybe adjusted as desired, this being, preferably, accomplished by varyingthe length of the stroke of the reciprocable member. Preferably,adjusting means is provided for varying the length of the stroke of thereciprocable member, which is provided with indicating means thereonshowing either the amount of liquid being pumped per stroke, or someother unit of measurement, or any arbitrary scale that may be decidedupon, to indicat e the desired adjustment. It is also desirable tooperate the reciprocable member in a manner that the discharge stroke isrelatively long and the suction stroke relatively short, so

as to reduce the intermittent character of the supply of liquid from thedischarge end of the pump, which necessarily exists due to the pumpingcycle, in a single chambered pump. Furthermore it is desirable, in orderto not have too great an inactive interval for the pumping device duringwhich no reciprocation takes place, that the valves open and closeabruptly, and suitable cam means for this purpose are, preferably.Provided.

Preferably, my improved pumping device is driven by a rotatable-member,which is provided with suitable means for reciprocating the reciprocablemember, and has directly rotatably mounted thereon to rotate therewith,the cam means for actuating the valves. It will be obvious that not onlycan the capacity of the pump during any interval of time be varied byvarying the stroke of the reciprocable member, but that this can also bevaried by varying the speed of the rotatable means for reciprocatingsaid member.

One of the purposes of my invention is to provide pumping means thatcomprises a diaphragm for varying the liquid capacity of the pumpchamber, and one of the preferred means for flexing the diaphragm tovary said liquid capacity comprises a bore, .or cylinder, in which areciprocable plunger, or piston, operates, the surfaces of the piston,and cylinder being of such hard material that these can be made to fitso closely that liquid interposed between said piston,

or plunger, and the diaphragm, will not leak 'past the engaging walls ofsaid piston and cylever, that I do not intend to limit myself to theparticular details shown or described, except as defined in the claims.

In the drawings:

Fig. l is a view partly in elevation and partly in vertical section ofone form of my improved metering pumping device.

Fig. 2 is a section taken on the line 2--2 of Fig. 1, on an enlargedscale.

Fig. 3 is a section taken on Fig. l, on an enlarged scale.

Fig. 4 is a section taken on the line 4--4 of Fig. l, on an enlargedscale.

Fig. 5 is a fragmentary section taken on the line 5-5 of Fig. 1, on anenlarged scale.

Fig. 6 is a view similar to Fig. 1, of another form of my invention.

Fig. 7 i a section taken on the line 1-1 of Fig. 6, on an enlargedscale.

Fig. 8 is a section taken on the line 88 of Fig. 6, on an enlargedscale.

Fig. 9 is a view partly in elevation and partly in section of theadjustable eccentric used in the form of the invention shown in Fig. 6.

Fig. 10 is a section taken on the line ill-l0 of Fig. 9, and

Fig. 11 is a view partly in elevation and partly in section of anotherform of my invention.

Referring in detail to the drawings, in Fig. 1 is shown a pumping devicehaving a frame 20, upon a portion of which is mounted any suitable meansfor driving a shaft, such as the motor 2|, which is shown as driving theshaft 22 through a worm drive reduction gearing, indicated at 23, saidshaft being mounted in suitable bearings 24 on the frame 28, and havingprovided thereon a main driving cam 25 and th valve cams 26 and 21, saidcams 25, 26 and 21 being fixed to said shaft to rotate therewith.

Mounted on said frame in any suitable manner in fixed relation thereto,is a pump chamber 28 made up of the sections 29 and 38, said sections 29and 30 being secured together in liquid tight relation by suitablesecuring elements 31 clamping the gasket 32 between suitable clampingfaces on said members 29 and 30. The member 30 is shown as beingprovided with an inlet passage 33 and an outlet passage 34. While theparticular shape of the chamber 28 may be varied, and the particulararrangement of inlet and outlet passages may also be varied, it isimportant that the inlet and outlet passages be so located that no airpockets can develop in the chamber 28, as no compressible gases must becontained therein, in order that the device will operate to measure theliquid passing therethrough properly.

The member 29 is, preferably, provided with a tubular projection 35having a bore 38, which serves as a cylinder for the reciprocation ofthe cylindrical plunger, or piston, 31 therein. A tight joint isprovided between the member 35 and the member 31 reciprocating therein,by providing a suitable packing gland arrangement made up of thecompressible packing 38, and the packing nut 39 engaging the externalthreads 48 on the member 35. The member 31 is reciprocated by means ofthe cam 25, said member 31 having an extension 4|, which operatesslidably through a suitable guide 42, and which is provided with abracket 43 on the end thereof having bifurcations 44 providing asuitable mounting for a pivot 45 for a roller 46, which engages the cam25 to reciprocate said member 31, it being, of course, obvious that theliquid capacity of the chamber 28, which comprises a portion or the bore38 the line 3-3 0:

for certain positions of the plunger, or piston, 31 will be varied inaccordance with the portion of the plunger, or piston, extending intosaid chamber 28 and its connected cylinder 36.

Means is provided for varying the amount of movement of the member 31 tovary the capacity of the chamber 28, the means shown varying the lengthof the return stroke so that the cam is only effective through a portionthereof when the stroke is reduced from its maximum. Any suitable meansfor varying the length of the stroke of the reciprocable member thatoperates in the chamber may be provided, the means shown comprising anadjustable stop member 41, which cooperates with a stop member 48 fixedto the extension of the member 31, a compression spring 49 being shownas being mounted between the member 48 and the nut 39 for retuming theplunger 31 from its furthest projected po. sition to make the roller 46follow the cam until the stop 48 engages the stop 41. The stop 41 ismade or such shape that the peripheral edge 50 thereof progressivelyextends from the pivotal axis of the member 41 a certain unit of measurefor each predetermined unit of arcuate movement of the member 41 aboutits pivot, in this form of the invention shown, the member 41 beingpivotally mounted on a headed pin 51, which screw-threadedly engages ina suitable threaded boss 52 in the frame 20, and which is provided withany suitable means, such as the cross bar 53 on the head 54 fortightening the same up when the member 41 has been moved to a desiredadjusted position. A scale 55 is, preferably, provided on the member 41and any suitable cooperating indicator, such as the knife edgeprojection 56, may be provided on the stop member 48 to indicate theadjustment of the member 41 to a desired length of stroke or volume ofliquid pumped per stroke, the scale shown being merely arbitrary and forpurposes of illustration, it being obvious that the same can becalibrated in any manner convenient to the operator of the device.

Referring to Fig. 3, it will be noted that the cam 25 is shown as beingkeyed to the shaft 22 and as having a cam surface made up of a lowportion 51, which is concentric with the axis of rotation of the cam anda high portion 58, that is concentric with the axis of rotation of thecam. Between said portions 51 and 58 is an outwardly curved portion 59,which is steep adjacent the portion 51 and becomes less steep as itapproaches the portion 58. Beyond the portion 58 is a gradually inwardlycurved cam surface 60, which is much longer than the outwardly curvedportion 59, and which extends to the portion 51. With the roller 46 inthe position shown in Fig. 3 and the cam rotating in the directionindicated by the arrow, the roller will first travel along the camportion 60 to move the piston, or plunger, 31 to the right in Fig. l,causing a gradual decrease in the liquid capacity of the chamber 28 andcausing discharge of the liquid through the outlet passage 34, if thevalve controlling the same is open. This movement will continue untilthe concentric cam face 58 is reached, whereupon there will be nomovement of the reciprocable member 31 until after said portion 58 hasbeen passed and the portion 59 -of the cam surface has been reached,whereupon the spring 49, which has been previously compressed, will movethe roller 46 toward the left, as shown in Fig. l, to keep said rollerin engagement with the cam surface 59 and, with a maximum stroke of thereciprocable member, this will continue until the cam surface 51,concentric with the axis of the cam 25, is reached, whereupon thereciprocation of the member 31 will be again halted until the cam face68 engages the roller 46, whereupon a repetition of the cycle ofmovements of the reciprocable member takes place. If the member 41 isadjusted to shorten the stroke of the plunger 31 from the maximum, thenthe roller 46 will leave the cam surface 59 dueto engagement of thestops, before the cam surface 51 is reached, and will not engage the camsurface 68 until a point thereon is reached beyond the junction of thecame surfaces 51 and 60, dependent upon the position of the adjustablestop member 41.

The inlet connection 33 extends from an inlet valve 6|, which leads froma supply pipe 62. Said inlet valve is illustrated as being provided witha diaphragm 63, which, when in engagement with the seat 64, closes thevalve so that no liquid can pass through the same in either direction,the inlet valve being shown as being closed in Fig. 1. It is, of course,understood that the valve seat 64 extends transversely of the passagethrough the valve 6| and that the diaphragm will engage the entirelength of said seat to completely cut off the chamber thus formed at 65in the valve 6| from the chamber formed at 66 on the other side of theseat 64. The diaphragm 63, preferably, comprises some compressiblematerial, which, when in engagement with the seat 64, will form a tightseal between said diaphragm and said seat, even though small solidparticles might adhere to the seat, the flexible material providingmeans for such small particles to bury themselves therein temporarily,so that these will not interfere with the sealing of the closure of thevalve. The diaphragm is connected with a reciprocable member, such asthe valve rod 61, in any well known manner, said valve rod having acollar 68 secured thereto and a compression spring 69 mounted betweensaid collar and the valve body portion, Said rod-like member 61 alsoextends through a guide member 18 provided on the frame 20 and isprovided with a bracket 1| secured to the end thereof, which is providedwith bifurcations 12 mounting a pivot member 13 for the roller 14 thatengages the cam 26.

Said cam 26 is provided with a highportion 15 and a low portion 16,which are concentric with the axis of rotation of the cam 26, said cambeing, of course, keyed to the shaft 22. Inclined connecting portion 11and 18 connect the low portion 16 and the high portion 15 of said cam.The compression spring 69 will hold the roller 16 constantly inengagement with the cam surfaces and the rotation of the cam 26 is inthe direction of the arrow shown in Fig. 4. The inlet valve being closedin the position of the parts shown in Figs. 1 and 4, the roller 14 willbe in engagement with the cam surface 15 until the inclined portion 11is reached, whereupon the terval and will then again close quickly, andthen again go through the same cycle of operations. The arrangement ofthe cams 25 and 26 on the shaft is such that the portion 15 of the cam26 will be in engagement with the roller 16 during the entire time thatthe roller 66 is in engagement with the cam surface 68, and the roller18 will still be in engagement with the cam surface 15 when the'camportion 58 engages the roller 46. However, as the roller 46 continues inengagement with the cam portion 58 the roller 14 engages the cam.portion 11, opening the valve 6|, said valve being completely opened andthe roller 14 in engagement with the cam portion 16 at the time that theroller 66 begins engagement with the cam portion 58 and this engagementof the cam portion 16 by the roller 14 continues until the cam portion51 has engaged the roller 46. However, during the major portion of theengagement of the cam portion 51 with the roller 46, the roller 18 is inengagement with the cam portion 18, so that the valve 6! is moved toclosed position before the roller 66 is engaged by the cam portion 60.Thus there can be no accidental backward flow of liquid through theinlet passage 33 and the valve 6|, and also no negative pressure createdin the chamber 28 by means of the plunger 31, as during the entiresuction stroke of said plunger 31, the inlet valve will be open, andduring the entire discharge stroke of said plunger the inlet valve willbe closed.

The outlet valve 19 is constructed in a similar manner to the valve 61and is connected with the discharge pipe 88 in a similar manner, theseat 8| of said valve 19 cooperating with the diaphragm 82 in a similarmanner to that pre-' viously described. The operating or valve rod 83 isconnected with the diaphragm 82 in the same manner as is the rod 61 withthe diaphragm 63 and the collar 84 and compression spring 85 I operatein the same manner as previously deroller will travel through a veryshort arcuate scribed. A guide lug 86 may be provided on the frame 20for the rod 83 and. a bracket 1|, such as previously described, isprovided thereon for mounting the roller 81 that engages the cam 21.

The cam 21 has a low portion 88, whichha's substantially the samearcuate extent as the high portion 15 of the cam 26, and a high portion89, which has substantially the same arcuate extent as the low portion16 of the cam 26. The inclined portions 90 and 9! connect the high andlow portions of the cam, the roller 81 being held in engagement with allportions of the cam surface due to the provision of the compressionspring 85. The cam 21 is related to the cam 25 in such a manner thatwhile the roller 81 is in engagement with the cam portion 88 and thevalve 19 is opened in consequence thereof, the roller 46 will be inengagement with the cam portion 60, and this engagement of the roller 81with the cam portion 86 will continue until the cam portion 58 engagesroller 86, whereupon the. outlet valve 18 will be closed due toengagement of the roller 81 with the cam surface 98, causing movement ofthe rod-like member 81 to the right, engagement of the cam portion 88with the roller 81 holding said valve in closed position until the camportion 91 is reached, whereupon the roller engaging the cam portion 8|under the influence of the spring will cause the valve 19 to be opened.Preferably, the cams 26 and 21 are so constructed that the valve 6| willnot open until the valve 18 has already been closed and the valve 6!will close before the valve 19 is opened. Thus, while the cam portions89 and 16 are of substantially the same arcuate extent, they arepreferably not of exactly the same arcuate extent, the angle measuringthe arc I6 being, preferably, slightly less than the angle measuring theare 89, thus assuring such operation of the valves as above referred to.

It will be obvious that with this arrangement of valve cams and drivingcam for the reciprocable pumping member, the intake action of the pumpwil be rapid and the discharge action of the pump will be relativelyslow and gradual.

If this is of no importance, an eccentric can be used to drive the pump,or a cross head arrangement can be used. If either of these types ofdrives are used, the cams that operate the valves will, of course, haveto keep the valves open through substantially half the stroke and thevalves will have to open and close during the reversal of motion of thereciprocable member at opposite ends of the stroke. In an eccentricdrive the rate of movement of the plunger, when the direction ofmovement reverses, is at first so very small that no harmful compressionin the pump chamber will result therefrom. Also this can be taken careof in utilizing a diaphragm pump, the movement of the diaphragm being sosmall that any increase in the pressure of the liquid that might resultmomentarily could be taken care or by the diaphragm. Such an arrangementis shown in Figs. 6 to 10, inclusive, the frame therein being indicatedby the numeral 20 and the pump chamber comprising the member 30,previously described, and a member 92, which is secured to the member 30by securing elements 93 to clamp the peripheral edge of the diaphragm 95between suitable seats on the member 30 and the member 92. Said member92 is provided with guiding means for the reciprocable rod-like member96, said guiding means comprising a tubular boss 91 provided on thespider-like body portion of the member 02. Said rod-like member 96 issecured to the diaphragm 95 in any suitable member so that a liquidtight chamber 98 is formed between the diaphragm and the member 30.

In order to protect the diaphragm 95 and prevent any undue flexingthereof adjacent the point of securement of the member 96 therewith, apair of concave-convex disk-like washers 99 are provided on oppositesides of the diaphragm 95. The end of the rod-like member 96 remote fromthe diaphragm is secured in a socket I of an eccentric sleeve IOI. Theeccentric sleeve and the adjustable eccentric provided in this form ofthe invention are shown more in detail in Figs. 9 and 10. The eccentricis mounted on a shaft 22, which is driven in the same manner as theshaft 22, previously described, and similarly mounted on the frame inthe bearings 24. The eccentric I02 is keyed to the shaft 22, as will beevident from Figs. 9 and 10, while the eccentric sleeve has mountedwithin the same and between the eccentric I02 and said sleeve IOI amember I03 that has an eccentrically located opening therein of the samediameter as the eccentric I02, so that said eccentric I02 and saidmember I03 are relatively rotatable to adjust the relative positionsthereof. The member I03 is freely rotatable within the eccentric sleeveI0 I and is shown as having an outwardly directed flange I04 and adetachable side plate I05 thereon forming a channel, this being merelyillustrative, as any suitable means may be provided for holding thesleeve IOI and eccentric I03 assembled for rotation of said eccentricwithin said sleeve. The

directed flange I08 cooperating with the side plate I05 to confine themember I02 therebetween.

The member I03 i adjustable to diflerent positions relative to themember I02 by rotation of the member I03 relative to said member I02, bymeans of the handle I01, so as to obtain a different length of strokefor the member I06. A clamp I08 held in clamping engagement with theeccentric member I03 by means of a screw-threaded headed member I08engaging athreaded opening in the eccentric member I02 holds the membersI02 and I03 in adjusted position. In Figs. 9 and 10 the parts are soadjusted that the rod 96 will not reciprocate, but by rotating themember I03 through 180 degrees the maximum throw of the eccentric andstroke of the member 93 is obtained, and, of course, any adjustmentbetween these two positions will give adjustments of the length of thestroke of the reciprocable member 96 between such maximum and minimumstrokes. Any suitable scale can be provided for indicating theadjustment of the member I 03 relative to the sleeve IN to indicate thedesired adjustment of the eccentric to get the desired throw thereof andthe desired stroke of the reciprocable member 96, such as shown in Fig.9. The particular clamping means for holding the parts in adjustedposition may be varied as desired.

The inlet connection 33 is connected with a conduit I09 and the outletconnection 34 is connected with a conduit H0. The conduit I09 isprovided with an inlet valve III and the liquid supply pipe 62 leadsinto said inlet valve. Said Inlet valve may be of any desiredconstruction, but is shown to be the same type of valve as the outletvalve, or discharge valve, H2, which is interposed between the conduitH0 and the discharge pipe II3. Each of said valves is provided with atapered valve H4 provided on a. rod-like member 5, and fixed in liquidtight relation to the member H5 is a disk-like member IIB, anaccordion-like diaphragm member I52 being secured at one end to themember H6 and at the other end to the valve casing to provide formovement of the valve rod H5 and to provide at the same time a liquidtight connection between the valve casing and said valve rod. The guidemembers I0 and 86, previously, described, are provided for the valverods H5, and said valve rods are provided with brackets II thereon, thatrotatably carry the rollers 14 and 81, similar to those previouslydescribed in connection with Fig. l. The roller 14 engages a cam H1 andthe roller 01 engages a cam IIB, both cams being keyed to the shaft 22,as will be obvious from Figs. '7 and 8. The rollers 81 and 14 are heldin engagement with the respective cams by means of the compressionsprings II9 provided between the members II and the collars 68 and 84,provided on the two rod-like members I I5, in a similar manner asdescribed in connection with Fig. 1.

In the position of the parts shown in Figs. 6, 7 and 8 the valve III isclosed and the valve H2 is open. However, the position of the parts issuch that the outlet valve member Ill in the outlet valve II2 will moveinto engagement with the seat I20 and the valve III will open uponslightly further rotation of the cams than that shown in Figs. 7 and 8.Also, when this takes place the diaphragm 95 will be flexed to the leftto increase the capacity of the chamber 98 due to the fact that theposition of the eccentric will be such that the rod-like member will bereciprocated toward the left, as viewed in Fig. 5.

The cam I H has a high portion I2I and a low portion I22, eachconcentric with the axis of rotation of the cam H1, and inclinedportions 923 and I24 connecting said high and low portions, whil the camII8 has a high portion I25 and a low portion I26 concentric with theaxis of rotation of the cam H8, and inclined portions I21 and I28connecting said high and low portions of the cam. The. rotation of thecams is in the direction of the arrows shown in Figs. 7 and 8.-

The roller 81, controlling the outlet valve, is in engagement with thelow portion of the cam in the. position shown, but the inclined portionI28 is just ready to engage said roller 81 so as to move the rod II 5,controlling the valve I I2, to

the right to seat the valve II4 against the seat I and close said valve.This occurs substantially instantaneously, as the arcuate distancetraveled by the cam H8 as said roller 81 rides along the inclined faceI28 is very short, and this occurs at the time the eccentric causes thereversal of movement of the reciprocable member 96, at which time themovement of said reciprocable member in the direction of its length isvery small compared with the amount of rotation of the eccentric thattakes place.

It will be noted that the roller 14, at the same time that the roller81: engages the low part I26 of the cam H8, is in engagement with thehigh part I2I of the cam I I1 and that this engagement continues for aninterval after-the cam portion I28 engages the roller 81, and thus theinlet valve will remain closed until the outlet valve has been closed,whereupon the roller 14 will engage with the cam surface I24 and ridedown along the same until the cam surface I22, or low portion of the camII 1, engages the roller 14, at which time the inlet valve I I I is wideopen, while the outlet valve is held closed due to engagement of thehigh part of the cam I25 with the roller 81. In a similar manner thevalve II2 will remain closed until after the inlet valve has again beenclosed, due to engagement of the inclined portion I23 of the cam II1with the roller 14 and the high portion I 2I thereof with said roller,this taking place when the reciprocable member 96 has reached the limitof its movement to the right, at which time the eccentric reaches apoint at which such reversal takes place, but the movement of the member96 in the direction of its length is very small in proportion to theamount of rotation of said eccentric. As a result there will be verylittle increase in pressure in the liquid in the chamber 98. due to thefact that both valves are closed while this slight movement of themember 96 is taking place under the action of the eccentric provided forrec procating the same.

In case the metering action of the pump does not have to be as accurateas would be the case where the forms of the invention shown in Figs. 1to 5, inclusive, and 6 to 10, inclusive, are utilized, the apparatusshown in Fig. 11 may be utilized to feed said liquid. The feed pipe I29is provided with a ball check valve I30 connected by the conduit I3Iwith an inlet connection I32, which leads into the liquid chamber I33provided in the member 30, the outlet connection I34 connected by aconduit I35 with a ball check valve I35 leading to the discharge pipeI31. A diaphragm I38 is clamped between suitable faces on the member 30and the member I39, which is provided with a threaded hollow boss I40thereon, with which a cylinder MI is connected in liquid tight.engagement. Said cylinder l ii is, preferably, made of a very hardmaterial, at least on the inner cylinclricalv surface thereof, providingthe bore 542, said cylinder being, preferably, made of an alloy that canbe nitrided, such as the alloy known as Nitralloy, manufactured by theLudlum Steel Company, which is a lowcarbon-manganesesilicon-chromium-molybdenum-steel alloy, containingaluminum. This alloy can be surface hardened so as to have such anextremely hard surface that it will not be scored and will not gald whenused in the manner illustrated. A plunger, or piston, I43 of acylindrical character is, preferably, made in a similar manner and issimilarly nitrided to surface harden the same, said piston fitting thecylinder so closely that liquid contained in the chamber between thediaphragm I38 and the body of the member I39 will not escape between thewalls of the piston, or plunger, and the inner surface of the cylinder,with which it slidably engages. This is possible because, due to theextreme hardness of the materiaLsuch a close fit can be provided withouthaving excessive friction. The reciprocable member can be driven in anyof the ways previously described, or can be driven by means of a rod I44pivoted thereto and connected with a cross :head'I45, so as to beadjustable relative to the center of rotation of the member I46 carryingsaid cross head, so as to vary the stroke of the piston, orplunger, I43by movement of the member I 41 in the slot I48 provided in the memberI45 rotating with the rotatable member I46.

A liquid, which is preferably thick, heavy and of high viscosity, suchas a heavy-bodied grease, indicated at I49, is provided in the chamberbetween said diaphragm I38 and the wall of the member I39, said liquidbeing substantially noncompressible and being, preferably, of acharacter that it has such a viscosity that there can be no escapethereof between the wall I42 and the piston I43, said liquid, of course,entering the cylinder bore I42 that communicates with the chamberbetween the diaphragm I38 and the casing I39, and it being obvious thatthe diaphragm will be flexed, dependent upon the position of the pistonI43, thus varying the capacity of the chamber I33 in accordance with theposition of said piston I43, thus drawing in fluid through the checkvalve I30 and discharging it through the check valve I38 in a well knownmanner.

What I claim is:

l. A metering pump of the character described, comprising a pumpchamber, a reciprocable member for varying the liquid capacity of saidchamber, driving means for said reciprocable member, an inlet connectionleading to said chamber, an inlet valve controlling supply of liquid tosaid chamber, an outlet connection leading from said chamber, an outletvalve controlling discharge of liquid from said chamber, said chamberbeing sealed whenever both said valves are closed, and means includingcams positively driven by said driving means for opening and completelyclosing said valves in positively timed relation to each other and tothe reciprocations of said reciprocable member, said driving meanscomprising meansfor moving said reciprocable member more rapidly in achamber capacity increasing direction than in a. chamber capacitydecreasing direc- 2. A metering pump of the character described,comprising a pump chamber, a reciprocable member for varying the liquidcapacity of said chamber, means for reciprocating said reciprocablemember including driving means, means for adlusting said means forreciprocating said member to vary the length of the stroke of saidreciprocable member, an inlet connection leading to said chamber, aninlet valve controlling supp of liquid to said chamber, an outletconnection leading from said chamber, an outlet valve controllingdischarge of liquid from said chamber, said chamber being sealedwhenever both said valves are closed, and means including camspositively driven in synchronism with said driving means for opening andcompletely closing said valves in positively timed relation to eachother, said driven means positively holding both said valves closed overpredetermined intervals, the means for reciprocating said memberincluding means for holding said reciprocable member stationary wheneversaid chamber is sealed.

3. A metering pump of the character described, comprising a pumpchamber, a reciprocable member for varying the liquid capacity of saidchamber, means for reciprocating said reciprocable member includingdriving means, means for adjusting said means for reciprocating saidmember to vary the length of the stroke of said reciprocable member, aninlet connection leading to said chamber, an inlet valve controllingsupply of liquid to said chamber, an outlet connection leading from saidchamber, an outlet valve controlling discharge of liquid from saidchamber, said chamber being sealed whenever both said valves are closed,and means including cams positively actuated by said driving means foropening and completely positively closing said valves in positivelytimed relation to each other and to the reciprocations of saidreciprocable member, said means positively holding both said valvessimultaneously closed over predetermined intervals, said means forreciprocating said member including means for holding said reciprocablemember stationary whenever said chamber is sealed.

4. A metering pump of the character described, comprising a pumpchamber, a reciprocable member for varying the liquid capacity of saidchamber, means for reciprocating said reciprocable member includingdriving means, an inlet connection leading to said chamber, an inletvalve controlling supply of liquid to said chamber, an outlet connectionleading from said chamher, an outlet valve controlling discharge ofliquid from said chamber, said chamber being sealed whenever both saidvalves are closed, and means positively actuated by said driving meansfor opening and completely closing said valves in positively timedrelation to each other, comprising means including a cam for openingsaid outlet valve before the capacity decreasing stroke of saidreciprocable member commences and holding said outlet valve open duringthe entire capacity decreasing stroke or said reciprocable member andmeans including a cam for opening said inlet valve before the capacityincreasing stroke of said reciprocable member commences and holding saidinlet valve open during the entire capacity increasing stroke of saidreciprocable member, said means positively holding both said valvesclosed for intervals alternating with the periods during which saidvalves are alternately held open, said means for reciprocating saidmember comprising means for varying the length of the stroke of saidreciprocable member between zero and full stroke without affecting therelation of said valve positions to the strokes thereof.

5. A metering pump of the character described, comprising a pumpchamber, a reciprocable member for varying the liquid capacity of saidchamber, means for reciprocating said reciprocable member includingdriving means, an inlet connection leading to said chamber, an inletvalve controlling supply of liquid to said chamber, an outlet connectionleading from said chamber, an outlet valve controlling discharge ofliquid from said chamber, said chamber being sealed whenever both saidvalves are closed, and means positively actuated by said driving meansfor opening and completely closing said valves in positively timedrelation to each other, comprising means including a cam for holdingsaid outlet valve open during the entire capacity decreasing stroke ofsaid reciprocable member, and means including a cam for holding saidinlet valve open during the entire capacity increasing stroke of saidreciprocable member, said means positively holding both said valvesclosed for intervals alternating with the periods during which saidvalves are alternately held open, said means for reciprocating saidmember comprising means for holding said reciprocable member stationaryduring the intervals during which both said valves are closed andincluding means for varying the length of the stroke of said reci ocablemember between zero and full stroke without affecting the relation ofsaid valve positions to the strokes thereof, comprising resilient meansfor moving said reciprocable member in one direction and an adjustablestop for limiting such movement by said resilient means.

LYNDUS E. HARPER.

